Radiocarbon dating of the iron production in slag-pit furnaces in Jutland

Radiocarbon dating of the iron production in slag-pit furnaces in Jutlan

Jernudvinding i Danmark i forhistorisk tid

Prehistoric Iron Smelting in DenmarkOf the various arrangements for iron smelting which have been employed in Denmark up to c. 1600, only those with slag pits will be discussed here. Usually, only the slag from these is preserved, most often fused into one large lump, which reproduces a portion of the pit shape, fig. 2.Nearly all earlier attempts at reconstruction are based on the assumption that the iron particles which are formed during extraction sink down through the fluid slag mass and collect at its base 1), but as examination of such accumulations "in situ" has never yielded traces of the extracted iron (bloom), this supposition is hardly acceptable. Both from the appearance of the slag block and from technical probing and experiment, as well as from ethnographical and historical sources, it can be assumed that a superstructure of clay has been erected over the slag pit. In this shaft the actual extraction has taken place, the iron being retained whilst the slag has run into a pit in the ground, where it has often solidified into one large Jump, the slag block. The construction of the superstructure is reproduced in a furnace shaft which was found at Scharmbeck near Hamburg in the 1950s 2). The necessary air supply was maintained through four holes and the chimney effect of the shaft presumably ensured a sufficiently powerful draught. The slag pit was probably quite empty apart from a plug of straw which closed the hole under the superstructure. This plug perhaps continued to the bottom of the pit as a cylinder, or was merely held in place by thin twigs. The slag first collected at the bottom of the superstructure and after a certain length of time the straw plug was perhaps sufficiently burned to allow the slag to run out, or was pushed down into the pit by means of a stick through one of the air holes.The metallic iron formed in the superstructure had a very low carbon content and consequently aggregated into a spongy mass which easily stuck to the sides of the furnace or perhaps fell to the bottom. When the slag had run away, the bloom was broken out of the furnace, which was subsequently repaired with clay and placed over an empty slag pit and a new smelting commenced.The new reconstruction of an iron smelting furnace with a slag pit, shown in fig. 1, is primarily based on observations made in 1961 during the investigation of 5 slag pits at Drengsted 4) in the south-western part of Sønderjylland. They were all confined to an area of less than 1 acre on a settlement site from the 5th century A. D. A radio-carbon dating of one of the pits to 210 ± 100 A. D. 5) indicates, however, that the smelting in all probability ante­dates the settlement. Only two of these pits, BV and EL, were entirely undisturbed; in the remainder the slag was entirely or partially taken up and it was not possible to ascertain whether this had happened in prehistoric times. The subsoil all over the site was glacifluvial sand, and there was no special lining of the pits.Slag pit BV (figs. 4-6) was first exposed from above, but in order to obtain the clearest information on the structure of the slag block, the ultimate examination was made from the side, as much of the loose soil in and near the pit being removed as possible without dislodging any of the slag, which was finally sectioned through the middle, roughly east-west, fig. 6. The depth of the pit under the present surface was 90 cm and the greatest width 105 cm. It can clearly be seen on the cleaned slag block, figs. 4-6, that the slag has run into the pit over a limited area, corresponding to a ring 30 cm in diameter roughly in the middle where the slag is highest. It is also clear that the slag has not filled the pit in one go, but that the process has been prolonged, sand slipping into the pit so that it has become filled with alternating layers of slag and sand. For the slag in the pit to have the structure and shape it has, there must have been a superstructure where the actual reduction of the iron oxide and melting of the slag has taken place. The temperature in the pit has at no stage been so high that the slag could melt there; this could be seen, for instance, by the fact that the sand on the inside of the pit was nowhere burned red. On top of the slag lay a quantity of red-burned clay with a slag-covered inner surface. Most of it had a loose structure but a few pieces up to 15 X 20 cm were found, probably deriving from the superstructure.In slag pit EL, which was c. 80 cm deep, only a median section was made, and as the slag was less coherent there, the photograph (fig. 7) does not so clearly demonstrate that the structure is identical with that of the block from pit BV; the amount of intruded sand has merely been somewhat less, so that the slag block resembles more closely a normal slag block (fig. 2). A different structure was observed down the middle of the central portion of the slag mass, where solidification had apparently not taken place in a rapid descent. On removing the slag a distinctive structure was observed in the middle (fig. 8), which must be the impression of straw, not loosely packed but compressed into a cylinder with a diameter of 20 cm or more. Centrally, at the bottom of the pit, was a thick layer of carbonised straw, just under 20 cm in diameter and 2-4 cm thick, which is no doubt connected with the straw impression on the underside of the slag. Both these phenomena are known from other slag pits and can be explained as evidence of a straw plug in the connecting pipe from the superstructure.In the straw from pit EL a score of seeds were found, identified by Hans Helbæk 6) as predominantly barley with a few seeds of wild oats. The radio-carbon dating of 210±100 A. D. was made on straw from this pit, and there is thus an established agreement in time between the use of the furnace and the basis of the radio-carbon dating, namely the harvesting of the corn.Most of the slag in pit EM had an unusual structure, the surface being lumpy and uneven (fig. 9), in contrast to the slag in the pits mentioned before, which was dense with a smooth surface. The cause of difference cannot be determined without practical experiment, but it is conceivable that the extraction in this case has completely failed. The weight of slag in this pit is also much less. In the middle of the pit bottom a thick layer of carbon was found and at the bottom of that, a layer of compressed straw, 20-25 cm in diameter, corresponding to the straw in pit EL.In the last two pits, EO and EP, the slag must have been taken up, and this may have happened either recently, because ploughing was hampered, or in antiquity, because large lumps of iron had fallen into the slag and had to be hacked free. In the lowest, undisturbed part of EO lay a 10-15 cm layer of thick pieces of charcoal (fig. 10), and in the middle, at the bottom of the pit, a lump of carbonised straw. In the disturbed part of the pit, apart from pieces of slag, lay a number of cakes of burned clay, with a slag-covered inner surface. They were up to 4 cm thick, and from the position of the slag drops on the inside, it was obvious that the pieces must have stood vertically. In one of them, the underside of which was apparently undisturbed, fig. 11, there were traces of a circular hole c. 5 cm in diameter, which was partially filled by slag. This was presumably the lowest portion of the shaft, and the curvature suggests a diameter of roughly 50 cm.The slag blocks of Jutland have a characteristic shape, fig. 2, which is connected with that of the pit. One slag block (fig. 12) of 171 kg, from Snorup, Tistrup parish, Ribe county, gives us an almost perfect cast of such a pit, as the slag has been hot enough to reach the bottom of the pit. Only the middle of the underside is missing, and here straw impressions can be seen, which can be related to the temporary bung. The slag pit in the reconstruction, fig. 1, has the shape of the slag block from Snorup. The majority of slag blocks from Jutland have a slightly different shape, but this is because the slag has rarely reached the bottom of the pit, before solidifying. The lower portion is thus lacking, the slag reaching correspondingly higher up in the cylindrical portion of the pit.None of the Drengsted pits contained a complete block as in fig. 2, but it is nevertheless reasonable to consider them as special variants of this type. The differences can be explained by the slag in the Drengsted pits not having had a sufficiently high temperature to remain fluid in the pits for even a short period, and in the case of pit BV there has moreover been an intrusion of sand as the slag has run in.Of the superstructure -the shaft- such characteristic parts are preserved, fig. 11, that one may assume that it has been of the same type as the shafts found at Scharmbeck near Hamburg, fig 13, which can be assigned to the 2nd century A. D. 2). From the slag-covered interior of these it is seen that the temperature up to 30 cm above the tuyeres has been higher than the melting point of slag.An estimation of consumption and yield in iron extraction has been based on Fr. Hupfeld's description of iron extraction in Togo in West Africa 13), J. W. Gilles' 1957 experiments 11) and Wynne and Tylecote's experiments 12) of the same year, and on this information the yield in furnaces with slag pits is fixed at 1/4 to 1/3 of the iron content of the ore. With 70% Fe2O3 in the ore and 60% FeO in the slag the yield of iron will be 15.5-23 kg per 100 kg ore, with an ore consumption of 127-143 kg. Charcoal consumption is put at at least 10 kg per kg iron.An archaeological dating of iron smelting sites is as a rule impossible, dateable artefacts lacking completely. True, potsherds have been found in connection with a few sites, but it is not established that these derive from pottery used in the smelting and they must therefore be regarded as secondary. The only dating method which can be employed here is the radio­carbon method, as sufficient carbonised straw or charcoal for such a procedure is present in most pits. At present, only one slag pit, EL from Drengsted, has been dated in this way, and the result was 210± 100 A. D. 5). This did not correspond with the age expected, as it was supposed that the slag pits belonged to the 5th century settlement investigated at the same place. This is a clear indication that slag pits cannot be dated by the pottery found on the site, consequently throwing doubt on many of the dates arrived at in the early literature. Before a comprehensive series of radio-carbon datings of different iron smelting sites has been undertaken, it is impossible to establish when these furnaces were first used in this country, and how long the technique survived.Slag blocks of the type described here are found in a large quantity in West and Central Jutland 14), but are at present not recorded from the rest of Denmark or from Scandinavia. This type can, however, be traced down into Central Europe along the rivers Elbe, Oder and Weichsel, in Germany, Poland and Czechoslovakia (fig. 20). The distribution area covers a broad belt outside the frontiers of the Roman empire and partially corresponds with the distribution of Roman imports, but the presence of iron-smelting furnaces can hardly be a direct result of Roman influence, as the Roman furnaces were of a quite different nature, without slag pits 15). As long as datings are so few and uncertain, it is difficult to have any well-founded views on the origin of the furnace with slag pit, but it is most probable that the technique has spread from the south-east towards the north-west.It is most likely that production has covered home consumption, but it is also possible, as suggested by Wielowiejski 16), that iron was to a large extent exported to the Roman empire. For the Danish finds to support such a hypothesis, a greater density of Roman import articles ought to be expected in the iron area of Jutland than in the rest of Denmark, where an equivalent iron production has yet to be discovered. If anything, it looks as if the distribution of slag blocks emphasises the connections demonstrated earlier between the Oder-Weichsel region and Jutland, in the centuries around the birth of Christ 17), but before these interesting cultural-historical problems can be illuminated further, it will be necessary to undertake complete investigations into a number of iron-smelting sites in Jutland and to carry out so many radio-carbon datings that the technique can be accurately placed in time. Further excavation of iron-smelting furnaces will, it is hoped, also contribute to a verification of the reconstruction offered here, the efficiency of which it is intended to prove by practical experiment.Olfert Vos

Dokumentationsproblemer indenfor arkæologien

Problems of documentation in archaeologyWhen documentation is spoken of in connection with archaeology, it is usually in the sense of the presentation of proof for the interpretation of observations made during excavation or during the study of artefacts, but documentation has another meaning: to collect, arrange, catalogue and retrieve all kinds of documents. By document is meant any communication made by man which has found a more or less permanent form. In all disciplines there is a continuous accumulation of various kinds of information, data, which at some stage will be used again to provide new knowledge, and these data must be arranged in such a way that they are easy to find again - information retrieval.The entire archaeological material -artefacts and descriptions of investigated monuments­ consists of such data, communications of a more or less permanent nature. This material is already enormous and is growing faster and faster. Numerous principles of arrangement, of varying practicability, corresponding to the equally numerous points of view involved in subsequent treatment of this material, are in existence. None of them ensures that the desired material can be retrieved irrespective of the approach. The ideal is the registration and arrangement of the necessary information in such a way that it is easy to find, whichever aspect is to be studied.An advanced and central documentation should seek to eliminate the following:1) The eventual loss of information which is stored privately or purely mentally.2) The inaccessibility of information which is recorded in an idiom which cannot be fully understood by an outsider.3) The repetitive elementary cataloguing which is the beginning of much research.4) The tedious or fruitless searching of different museum store-rooms for analogous material which has been dispersed according to the particular arrangement employed in storage.5) Wear and tear on objects and archives caused by repeated searching.Just as mechanization transferred much labour from a purely muscular to a controlling role, an advanced documentation should free scholars from the tedious and repetitive searches of large collections of material and give them time and energy for more creative work. But just as artisans were opposed to the mechanization of their trades and consequent devaluation of their skills, opposition can only be expected from many whose memory will be made partly superfluous by such documentation, which is basically a mechanization of memory.The question is thus not whether there should be a National Index to carry out documentation in the future, but rather how this work should be organized and how it should function. To clarify this problem, it will be necessary to look at the data and methods of archaeology. In respect of the latter, it can be stated in general that the basis for the conclusions one may extract from the material remains, which are preserved in the form of artefacts or monuments, is the study of similarities and differences, what Sophus Müller called archaeological comparison [1].There are many kinds of similarity. Similarities of external form and decoration are not the only ones: there are also affinities of material, mode of manufacture, size and context. Similarity cannot be measured directly and there are many degrees between dissimilarity and identity, but when groups are drawn up, the number of similarities can be counted. The smallest units which can exhibit similarities and differences are called by Malmer [2] typological elements, by Moberg [3] elements of similarity, but here merely elements. They can be divided into elements of shape, of proportion, of decoration of material, and of mode of manufacture [2].The affinities we employ in studying archaeological material are 1) similarity between combinations of elements, expressed in types, and 2) similarity between combinations of types (artefacts and monuments) which are embodied in units of various kinds: cultures, periods, phases, horizons, etc.A type can be defined by the number of well-defined elements which repeatedly occur together in a group of objects in a limited geographical area and inside a limited period. The number of such elements drawn into the definition can vary, and if it falls below a certain minimum, it would be natural to speak not of types, but of species.The types we work with are usually defined from only a few elements, but this does not mean that a description can ignore the other elements. These may later form the basis for a subdivision of the type -chronological, geographical or functional- or for an entirely different typological division of the material when it is approached from another direction. It is thus impossible to decide beforehand which elements can be omitted in a description of archaeological material.The concept of type has an essential function in the study of material, as it is with its help that one makes generalizations, whereby equivalent observations made in connection with several examples of the defined type are taken to be valid for all, for example dating, determination of the place of manufacture, determination of function -as long as there is nothing to invalidate them directly.The task of creating a National Index for Danish artefacts and monuments, originally projected by Harald Andersen, Mogens Ørsnes and the author on entirely traditional lines, has now been taken up by the Institute of Prehistoric Archaeology and Ethnography of the University of Aarhus. The main register in this National Index will be a card index in format A4 (29. 7 X 21.0 cm), fig. 1, where each card will record information and carry a drawing and/or photograph of one artefact or one monument. This part of the project, the development of the traditional index cards, has been commenced, and simultaneously we are attempting more systematically to establish which needs a National Index should and can meet if it is to be at all practicable. In order to ensure that the assembled information will be clearly expressed and easily accessible -the prerequisite if a system is to have any permanence- it has been necessary to study the problems of registration and description affecting related disciplines, the various indexing systems, etc. Electronic data processing has also opened new perspectives for information retrieval.An ordinary card index is merely a subject -divided list of documents which has been split up into cards with one document, for instance a book or an artefact, on each card.One has thereby achieved an open system where new documents can be inserted and new subjects added. If this system is to work satisfactorily however, there are certain rules which have to be followed: the subject-matter has to be divided into a series of main categories, which may only be subdivided one at a time in a hierarchical system.The subject-matter of the National Index is artefacts and monuments, each of which can be divided into a number of main categories, species, which are recorded in a register or list of species. As a sub-division of the species, for example axes, one would have the different types of axe. This requires, however, that true definitions of type are employed, and these have been virtually non-existent in archaeological literature until recently. Malmer's complaints of non-definition [4] are fully justified, and if one is to catalogue a large material with no other purpose than to create an order which will make it easy to find things, definitions are an absolute necessity.The typological division of the Danish material is based on Sophus Müller's "Ordning af Danmarks Oldsager" 1888-95, which was superseded in respect of the Stone and Bronze Ages by "Danske Oldsager" 1948-53, edited by Therkel Mathiassen. These works provide illustrations of "all Danish artefact types" together with a short description, which, however, does not include any clear delimination of the types. In identifying an artefact, one will therefore often be in a position where certain affinities will call for allocation to one type and others to another type. The type divisions for one species are often based on quite different criteria, for instance core axe and flake axe (mode of manufacture) contra round-butted axe (shape) or silver-sheet fibula (material) contra relief-fibula (decoration) and fibula with semi-circular plate (shape).The rule for the addition of new subjects, types, to a card index is that this may only occur by sub-division of one category at a time, in our case of one descriptive element at a time. One step in the classification of pots can thus comprise the neck: concave, straight or convex, and the next lugs: absent, one, two, three or more lugs. It will facilitate searching if the most frequently employed categories, the descriptive elements, are divided first. In the above example, pots with one lug must be sought in three different groups, if we let lug-classification be subordinate to neck-classification, whereas we would only have to look in one place, if neck-classification were subordinate. It is apparent that the more descriptive elements are employed, the more difficult it is to find a particular element in a hierarchical card index. One further example will make this clearer. In a telephone book, where the names are ordered alphabetically, we have a hierarchical arrangement of a large material. In the case of artefacts, we cannot know beforehand which category should be placed first, corresponding to the first letter in a name, as we may need to find any element, rather as if we had to find in the Danish telephone directory all the names ending in -sen. An index of artefacts or monuments built up on these hierarchical principles would become increasingly difficult to work with as it grew. The difficulties involved in the actual description are equally formidable.The ordinary description of artefacts frequently makes use of a division into a series of naturally deliminated parts, which are then described separately: for example a pot can be broken down into body, shoulder, neck, rim, base and lugs. There is though, neither agreement as to how the individual parts should be demarcated nor as to the meaning of the terms used in description. On index cards photographs and drawings can to a certain extent replace a description, but often there are observations which cannot be illustrated. Illustration of all objects would also be an expensive and time-consuming process, but the main objection is that it does not contribute to cognition, which actually depends on a division into elements and a naming or classification of these. If we are to have an index within a reasonable period of time, which will fulfil the need for documentation, it will not be possible to draw or photograph everything, and we shall be forced to make do with descriptions which are as complete as possible.The description system of Jean-Claude Gardin The French archaeologist Jean-Claude Gardin [5], director of the Centre d'Analyse Documentaire pour l'Archéologie (CADA) under the Centre National de la Recherche Scientifique (CNRS), has been engaged for several years (see bibliography) on the same problems of documentation which we are now encountering, and has shown in several publications how these problems can be solved. Gardin starts from the principle that the most accurate and complete description comprises the definition and organization of a large number of elementary features, and to this end he has evolved a general procedure, an analytical description, employing a special language of symbols.First Gardin lays down rules for the orientation of the object to be described, so that reference can be simplified: right/left, upward/downward, front/back, for example. Pots, for instance, are placed with the base horizontal and tools with the long axis horizontal, the functional part to the right and the handle to the left.Next he divides the object in largely traditional manner into parts, for example neck, body, base, etc., in the case of pots. This segmentation is to a certain extent given by normal linguistic practice, which is itself an expression of the similarity of form occurring in each of the main functional categories. These categories, here called species [6], are for example, fibulae, pots, axes, ploughs. For the sake of clarity of description, however, it is necessary to lay down clear rules for the segmentation of each species into parts. Examples of such a segmentation are seen in figs. 7 and 12. Besides shape, ornament, material and mode of manufacture, there are other data which must be included in the description the nature of the find, i. e. grave, settlement, hoard, etc., and its context, i. e. whether it is an isolated find or whether it can in some way be combined with other objects by being of a single find, of a documented combination, or of a structure with a clear stratigraphy, i. e. together with, over or under other objects one would wish to feature in the description.The last part of the system of description is the differentiation which consists of a break­down of the variations in which the different parts can occur. In Gardin's experience [7], one can generally be satisfied with broad divisions only providing a small number of qualitative differences. These are easily observed (e. g. straight, convex, concave -parallel, divergent, convergent- larger than, equal to, smaller than) and together cover the entire range of variation of each part. Quantitative elements -absolute or comparative values- need only be used to a minor extent and when they are employed, are arranged in groups of varying range according to the material being treated, for example, length can be grouped < (less than) 5 cm, 5-10 cm and > (more than) 10 cm.The vocabulary necessary for a description of this kind is remarkably small, usually less than 40 terms used in each of the parts into which the object is divided. The parts and their various shapes are expressed by symbols, so that the description of each part comprises two or three symbols, for example Bc, of which the first capital refers to the part, here the body of a pot, and the small letter and/or number to one of the categories this is divided into, here with smooth transition from lower to upper half. The traditional synthetic terms have thus been replaced by analytical formulae.These descriptive formulae are ideally suited to transference to punched cards and data processing machines. Gardin has also shown that they permit a simple solution to the problem of arranging the catalogue cards, as these can simply be numbered and arranged numerically under each species. Then an index is compiled to this numerical catalogue, containing one card for each of the variations into which the different parts are divided. This feature card gives the numbers of the requisite numbers in the catalogue. This system is called "inverted filing". On a special kind of index card -the so-called "peek-a-boo" cards- all the catalogue numbers are printed in advance. One denotes that a certain number in the catalogue has the property in question by punching the card in the number position, fig. 2. In this way, one can retrieve combinations of a whole series of properties.The meaning of the symbols and the rules for segmentation are given in the code which is accompanied by an explanatory commentary.The code is divided into chapters, denoted by capital letters, corresponding to the parts of the objects, and in each chapter there is a list of the possibilities for expressing the variations in each part. Two examples will give an impression of the nature of the code. The first is from the pottery code, chapter B (the body of the pot), fig. 3 illustrating the profile of the body. In most of the symbols employed there is a mnemotechnical content: v = concave, d = droit, x = convexe, i = divergent, u = parallele (the shape of the letter), o = convergent. The schematic vessel profiles in the figure are thus denoted by vi/xo, the profile being read from below upwards.Fig. 4 refers to the conjunction between the upper and lower parts of the body: c = curved or continuous transition (continu), I = angular or discontinous transition (I is the normal mathematical symbol for an angle), q = discontinuous transition which combined with x (convex) to qx denotes a moulding and with v (concave) to qv a fluting, z = a broken line which combined with i (diverging) to zi denotes a diverging angle and with o (converging) to zo a converging angle. From the pottery code's chapter E (the neck), fig. 5 refers to the conjunction between body and neck and we can see that the meaning of the symbols is exactly as above. This is a good example of one of the principles of coding: the choice of a description so simple that it can be employed on different parts and also on different kinds of objects.In other cases, as for example in chapter J (the cross-section of the lug or handle), the variations are merely numbered, fig. 6.The actual analysis is not so difficult as the development of the code, but can naturally be rather a lengthy process if it covers a large or very complex material. The work is reduced with the aid of special forms for analysis, which contain directions and often a printed list of alternatives which have merely to be underlined, so that a single form can be completed in a few minutes or less. These systematic analyses take much less time than a normal description and are moreover both comprehensive and precise. To minimize the inevitable subjectivity involved in observation, the analysis is carried out by two persons independently and the result checked by a third. A sample pottery analysis form is shown in fig. 8.The second of Gardin's artefact codes, the code tools and weapons, is constructed on the same principles. Here, the descriptive parts are divided into two groups, one comprising the functional parts and the other the hafting or handle parts, fig. 12, and each group is divided as usual into a series of chapters with capital letter headings, thus:I GeneralA Functional partB HaftingC Dimensions, absolute and relative II Functional partD Section, facesE Section, sidesF Outline, upper sideG Outline, lower sideH Outline, "end" and conjunction of sides and "end" I Details III Hafting partJ SectionK Outline, upper sideL Outline, lower sideM The shape of the termination in a plane parallel to the functional partN The shape of the termination in a plane at right-angles to the functional part0 Appendages of the hafting part.P DetailsIV Connections between II and III Q Conjunction of K and FR Conjunction of L and GS Conjunction of N and E The terms "upper" and "lower" are defined according to the rules for orientation mentioned above.Two examples from this code will show that it is not very different from the pottery code and that several symbols are used again with the same meaning.The first example, fig. 9, is from chapter A and shows a division into functional types, merely numbered in succession. Fig. 10 is from chapter D (cross-section of the functional part). Note that several of the symbols have been employed before in the pottery code with the same meaning: d = straight, c = curved or continuous transition, 1 = angular or discontinuous transition, n = discontinuous transition with angles in direct succession, Ø = ending in a point. Fig. 11 is from chapter F (the contour of the top of the functional part). To make it possible to describe a change in the curve, the contour is divided into two parts, each with its own symbol in the vertical column where the terms d = straight, x = convex, and v = concave are seen in different combinations. In addition, the course of the curve may be characterized by three terms Ø, I and II, denoting that the end points of the curve and the point where it changes course are in the same plane, Ø, or that the latter point ties respectively above, I, or below, II, the line joining the two end points. Each of these denotations is then augmented in three columns, according to whether the point where the curve changes direction lies to the left (<), in the middle (=) or to the right (>).Also the implement code has its special forms for analysis, divided as for the pottery code into parts (capital letters) and a number of variables (small letters and numerals). A sample completed description sheet for an implement is reproduced in fig. 13.*The development of systems of description like those mentioned here can be a valuable contribution to archaeological scholarship by establishing a firm conceptual system, which should be the basis of the national systems, which are under constant revision. Gardin's analytical system is not dependent on the language in which it is compiled, as the conceptual content of the symbols is well defined and constant, irrespective of the language employing them. This is by no means true of normal archaeological concepts. For instance, the term microliths comprises in 1) Danske Oldsager I, no. 3, trimmed implements manufactured from blades 2-5 cm long and about 0.5 cm wide, though nos. 76-91 of the same work place the width between 0.5 and 1 cm; 2) according to Malmer [10], trimmed implements manufactured from blades with a maximum length of 5 cm and a width less than, or equal to, 1/5 of the lenght, i. e. 1 cm; 3) according to Childe [11], small implements less than 1 (or 1.5) inch (2.5-3.8 cm) long, which may have been manufactured from large blades -the definition must also include transverse points; and 4) according to Therkel Mathiassen [12], besides what Danske Oldsager calls microliths, also broad trapezes and rhomboids (oblique points) and to a certain extent transverse points.This example is not unique. It is, s

Portal. Ovnstypologi og ovnskronologi i den nordiske jernvinna. Jernvinna i Oppland. Symposium på Kittilsbu, 16-18. juni 2009.

Norden må på mange måter betraktes som et enhet­lig område. Innenfor den arkeologiske forskningen finnes det klare paralleller i utviklingen i de nordiske landene, selv om det også eksisterer en rekke forskjel­ler. I studier av forhistorisk tid og middelalder ope­reres det med nordisk arkeologi som et eget felt sett i sammenheng med europeisk og klassisk arkeologi. Jernvinneforskningen er ikke noe unntak i så måte. Jernvinneforskningen har i en årrekke hatt et internasjonalt tilsnitt, og det er interessant å se at de nordiske landene ofte deltar på konferanser ut fra egne premisser, som skiller seg ut fra det øvrige Europa. Denne fragmenteringen kan skyldes flere ulike faktorer. Svært sentralt her er de klimatiske, topografiske og geologiske betingelsene vi finner i Norden. Og den kanskje viktigste faktoren er at de nordiske landene, sammen med det nordlige Øst-Europa, er omtrent enerådende når det gjelder bruk av myrmalm i jernblestringen. For øvrig er det i hovedsak bergmalm som ble brukt i den tidlige jernproduksjonen. Til tross for de store likhetene som finnes i den nordiske jernvinnehistorien, har faget etter hvert blitt fragmentert også her. Tidligere var det svenske Jernkontorets høstmøter en felles arena for nordisk kontakt, men manglende aktivitet, fravær av ild­sjeler og den omfattende svenske tilnærmingen til masovnproduksjonen i de senere år har ført til at forumet delvis har falt bort. Jernvinneforskningen har derfor beklageligvis utviklet seg med vekt på nasjonale funn uten at noen har klart å sette disse inn i en bred nordisk kontekst. Etter vår mening er den nordiske konteksten helt sentral for å kunne forstå kontaktveier og innovasjonsprosesser. Den rent faglige bakgrunnen for symposiet på Kittilbu og den påfølgende publikasjonen er et direkte resul­tat av et ønske fra norsk side om å reetablere, kart­legge, sette sammen og systematisere den nordiske jernvinneforskningen til en naturlig felles enhet